1. Field of the Invention
The present invention relates to a navigation device for displaying a road map, a guide route, etc. on a display according to operations performed by a user, and for providing navigation services.
2. Description of the Prior Art
Conventionally, a navigation device for providing the current position of a vehicle, in which the navigation device is mounted, to a driver or user and for showing a route to a destination is well-known. In general, the navigation device calculates the current position of the vehicle by using a GPS (global positioning system) which uses eletromagnetic waves from GPS satellites, a vehicle speed pulse from a counter disposed at, for instance, an axle, and a gyro, etc., and displays the current position of the vehicle on a display with a map being displayed based on a map database. When the driver sets a destination, the navigation device calculates an appropriate route according to a fixed method, such as Dijkstra""s algorithm, by referring to the map database, displays information on the route on the display, and outputs a voice guidance from a speaker, to guide the user to the destination. The route guidance thus includes display of the calculated route on an on-screen map, and, when the vehicle approaches an intersection for example, output of voice guidance such as xe2x80x9cturn rightxe2x80x9d or xe2x80x9cturn leftxe2x80x9d and display of a guidance image showing the intersection.
FIG. 25 is a diagram hierarchically showing the structure of a prior art navigation device disclosed in xe2x80x9cDevelopment of a New Platform of a Navigation System for Vehiclesxe2x80x9d, xe2x80x9cSumitomo Electricityxe2x80x9d issued by Sumitomo Electric Industries, Ltd., No. 148, pp. 37-41, March, 1996. In the figure, reference numeral 201 denotes navigation hardware including a remote controller, a drive unit for driving a storage medium, such as a CD (Compact Disc)-ROM, for storing a map database, a display, and a GPS receiver, numeral 202 denotes a navigation OS (operating system) having basic functions to control the navigation hardware 201, numeral 203 denotes device drivers for directly controlling a corresponding item of navigation hardware 201, and numeral 204 denotes a navigation application for calculating current position, route calculation, route guidance, and display of a map, etc. based on various information from the navigation hardware 201, and for providing navigation services for users. This prior art navigation device has a ROM for storing these programs, a microprocessor for executing them, etc.
In operation, the navigation application 204 is executed on the navigation Os 202, an event generated by each item of navigation hardware 201 is processed properly, and navigation services are provided. Thus, the prior art navigation device provides navigation services. The navigation application 204 of such the navigation device can be developed on a general-purpose OS installed in a personal computer. In other words, the navigation application 204 can be developed on a platform consisting of a personal computer and a general-purpose OS. The navigation application 204 is then transplanted on the platform 205 shown in FIG. 25, which consists of the navigation hardware 201, the navigation OS 202, and the device drivers 203 after the application has been completed.
A problem with prior art navigation devices constructed as above is that since there is a difference between hardware in development and real machines, and a difference in the hardware of different types of real machines, transfer of various information between the navigation application 204 and the navigation OS 202 depends on the platform, and it is therefore necessary to modify the navigation application 204 when transplanting the navigation application 204 onto another platform, thus increasing the complexity of the development work of the navigation application 204.
Japanese patent application publication (TOKKAIHEI) No. 11-211489 discloses another prior art navigation device. In this prior art navigation device a part of program is written in Java(trademark). Although it is a common one in different platforms, it is difficult to solve the above-mentioned problem since the navigation basic operations such as the route calculation are performed as in the above-mentioned prior art navigation device.
Furthermore, when changing the specifications of the map database, the navigation application 204 must be changed according to the change of the map database, and the complexity of the development work of the navigation application 204 therefore increases.
In addition, when changing the man-machine specifications, such as the specifications of the user interface, the navigation application 204 must be changed according to the change of the map database, and the complexity of the development work of the navigation application 204 therefore increases.
When changing the navigation application 204, if necessary, as mentioned above, the same amount of work and hence the same amount of debugging and testing work as in the case of creating a new navigation application are needed, thereby prolonging the time period required for development and increasing development cost.
The present invention is proposed to solve the above-mentioned problems, and it is therefore an object of the present invention to provide a navigation device that is implemented via a computer program to provide navigation services which is divided into a platform-dependent part and a platform-independent part, thereby decreasing the amount of needed changes in the program which originates in a change of the platform, and that thus can be easily developed.
It is another object of the present invention to provide a navigation device that reads map data from a map database in a fixed recording format, and supplies map information corresponding to it to a navigation application in a constant format, thereby decreasing the amount of needed changes in the program which originates in a change of the recording format of the map database, and that thus can be easily developed.
It is a further object of the present invention to provide a navigation device that receives data generated by a user""s operation with a predetermined user interface, and supplies operation information corresponding to it to a navigation application in a constant format, thereby decreasing the amount of needed changes in the program which originates in a change of the specifications of the user interface, and that thus can be easily developed.
In accordance with an aspect of the present invention, there is provided a navigation device comprising: a platform having hardware including at least a user operation unit and a map database, and basic functions to control the hardware; an application processing unit for providing navigation services by using the basic functions of the platform; and a platform-dependent unit for, when transferring information from the platform to the application processing unit, transferring it in a constant format, and for, when transferring information from the application processing unit to the platform, transferring it in a certain format which depends on the platform.
In accordance with a preferred embodiment of the present invention, the map database holds map data in a predetermined recording format, and the device further comprises a map-database-dependent unit for receiving map data, which is read from the map database by the platform-dependent unit, and for supplying the received map data to the application processing unit in the constant format.
In accordance with a preferred embodiment of the present invention, the navigation device further comprises a user-interface-dependent unit for receiving data corresponding to a user""s operation, which is read from the user operation unit by the platform-dependent unit, and for supplying the received data to the application processing unit in the constant format.
In accordance with another aspect of the present invention, there is provided a navigation device comprising: a platform having hardware including at least a user operation unit and a map database for holding map data in a predetermined recording format, and basic functions to control the hardware; an application processing unit for providing navigation services by using the basic functions of the platform; and a map-database-dependent unit for receiving map data read from the map database, and for supplying the received map data to the application processing unit in a constant format.
In accordance with a further aspect of the present invention, there is provided a navigation device comprising: a platform having hardware including at least a user operation unit and a map database, and basic functions to control the hardware; an application processing unit for providing navigation services by using the basic functions of the platform; and a user-interface-dependent unit for receiving data corresponding to a user""s operation, which is read from the user operation unit, and for supplying the received data to the application processing unit in a constant format.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.